An Australian cardiovascular risk equation for type 2 diabetes: the Fremantle Diabetes Study

Abstract

There is no valid cardiovascular disease (CVD) risk prediction equation for Australians with diabetes. The aim of this study is to develop and validate a multivariate risk function for 5-year cardiovascular risk prediction in Australian type 2 diabetes patients. The Fremantle Diabetes Study is a community-based longitudinal observational study. A total of 1240 type 2 diabetic patients (95.8% of the baseline cohort) with all required risk factor data were followed from baseline (1993-1996) for 5 years or until they experienced a cardiovascular event or died, whichever came first. CVD during follow up was defined as hospitalization for/with myocardial infarction or stroke, and death from cardiac or cerebrovascular causes or sudden death. Validation of the algorithm was performed on an independent diabetic cohort from the Busselton Health Study. During 5570 patient-years of follow up, 185 (14.9%) had at least one CVD event and 175 (14.1%) died (57.7% from CVD). Variables in the final model comprised age, sex, prior CVD, ln(urinary albumin : creatinine ratio), lnHbA(1c), ln(high density lipoprotein-cholesterol), Southern European ethnic background and Aboriginality. The mean 5-year predicted risk of a CVD event was 15.5%. Applied to the Busselton cohort, discrimination of the model was good (AUC = 0.84, P < 0.001) as was the goodness-of-fit (Hosmer-Lemeshow C-test, P= 0.85) and accuracy (mean squared error (95% confidence interval) = 0.09 (0-0.76)). The positive and negative predictive values for a 10% 5-year CVD risk cut-off were 23.4% and 97.7% respectively. This simple diabetes-specific 5-year CVD risk equation is the first validated, population-based Australian model. It should have a role in diabetes management in primary and specialist care.